ABSTRACT
This chapter explores the previously described data on the I-region of the guinea pig and focuses on a description of recent experiments applying monoclonal antibodies to guinea pig Ia antigens. The first immune response (Ir) gene was discovered in the guinea pig in 1963. Ir genes control the ability of an animal to mount an immune response to T-cell dependent antigens. The serological and genetic characterization of the guinea pig major histocompatibility complex (MHC) has been hampered by the lack of inbred strains and of informative recombinants. Ia antigens were demonstrated with alloantisera on lymphoid cells, but were absent on a number of carcinogen or viral induced hepatomas or sarcomas. Monoclonal antibodies to Ia antigens have allowed us to resolve the question whether the inhibition of Ir gene controlled funtions by anti-Iasera is actually mediated by antibodies to Ia antigens.
